Integrated seismic monitoring system and method

ABSTRACT

An integrated seismic system and method for monitoring seismic parameters of a subsurface structure is provided. The integrated seismic system includes a plurality of mobile satellite nodes, a seismic cable and a base station. Each of the mobile satellite nodes has sensor stations operatively connectable thereto for collecting seismic data from the subsurface structure. The seismic cable operatively links the plurality mobile satellite nodes and the sensor stations. The base station includes a seismic acquisition unit for receiving seismic signals from the mobile satellite nodes via the seismic cable and generating seismic parameters therefrom.

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 61/608,345, filed on Mar. 8, 2012, the disclosureof which is incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates generally to techniques for investigatingsubsurface structures. More specifically, the present disclosure relatesto optical monitoring systems for measuring seismic parameters ofsubsurface structures.

The exploration of oil and gas may involve the investigation ofsubsurface structures, such as geological formations and/or reservoirs.Seismic sensing systems may be positioned about a surface location forsensing properties of the subsurface structures. Such properties mayinclude physical properties, such as pressure, motion, energy, etc. Suchproperties may occur naturally, or may be generated by imparting a forceto the surface using a seismic energy source (e.g., a seismic vibrationtruck). Examples of seismic vibration trucks used for generating seismicvibrations are provided in US Patent Application No. 2009/0238038. Thereflected seismic waves generated by the seismic energy source may becollected and analyzed to determine characteristics of the subsurfacestructures.

Techniques have been developed for sensing seismic parameters. Examplesof such techniques are provided in US Patent/Application Nos.20080062815, 20080060310, and 20080060311. Some seismic sensing systemsmay be, for example, optical systems including seismic trucksdistributed about a location for independently collecting seismic data.Each seismic truck may have fiber optic cables with optical sensorsdistributed about a surface of a subsurface structure. The seismictrucks may also have a light source for emitting a laser through thefiber optic cables. The light source distributes light to and collectslight from the optical sensors positioned along the fiber optic cables.The seismic truck may have devices for detecting changes in the light.Such changes may be used to determine information about and generateimages of the subsurface structures. Examples of optical systems andsensors are provided in U.S. Pat. Nos. 7,622,706, 7,222,534, 7,154,082,and 6,549,488.

Despite the development of advanced techniques for optical seismicmonitoring, there remains a need to provide advanced techniques forperforming optical seismic monitoring. The present subject matter isdirected to fulfilling these needs in the art.

SUMMARY

The present disclosure relates to an integrated seismic monitoringsystem positionable about a surface location to form an integratednetwork for collecting seismic data relating to subsurface structures.The integrated seismic monitoring system includes a base station, aplurality of mobile satellite nodes, and a seismic cable. The pluralityof mobile satellite nodes has sensor stations operatively connectablethereto for collecting seismic data from the subsurface structure. Theseismic cable operatively links the plurality of mobile satellite nodesand the sensor stations. The base station includes a seismic acquisitionunit for receiving seismic signals from the mobile satellite nodes viathe seismic cable and generating seismic parameters therefrom.

The seismic cable may include a fiber optic cable and the base stationmay include a light source for sending and receiving a light through thefiber optic cable. The seismic cable may link the base station to themobile satellite nodes in series. The satellite nodes may be seismictrucks. The fiber optic cable may include fiber optic sections coupledtogether. The seismic acquisition unit may include recording media(e.g., tape drives and/or raid drives), a source controller, anacquisition management system, spread & opto-electronics, and/or ageneric acquisition system. The seismic cable may link the satellitenodes to the base station in a looped, a linear, a star, and/or aconcentric ring configuration. The sensor stations may be connected tothe satellite node by array cables.

The present disclosure also relates to an integrated method formonitoring seismic parameters of subsurface structures. The methodinvolves providing an integrated seismic system including a base stationand a plurality of mobile satellite nodes (each of the satellite nodeshas sensor stations operatively connectable thereto), linking the mobilesatellite nodes and the sensor stations with a seismic cable, collectingthe seismic data from the subsurface structure with the sensor stations,and receiving seismic signals at a base station from the mobilesatellite nodes via the seismic cable and generating seismic parameterstherefrom.

The method may also involve sending and receiving a light from a lightsource at the base station through the seismic cable and to the sensorstations, positioning the mobile satellite nodes and the sensor stationsabout the subsurface location, analyzing the measured seismicparameters, processing the measured seismic parameters, generating aseismic disturbance at the surface location, and correlating a positionof the sensor station (e.g., a GPS location) with the seismicparameters.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the subject matter, briefly summarizedherein, may be had by reference to the embodiments thereof that areillustrated in the appended drawings. The figures are not necessarily toscale, and certain features and certain views of the figures may beshown exaggerated in scale or in schematic in the interest of clarityand conciseness.

FIG. 1 shows a schematic view of an integrated seismic system formonitoring seismic parameters of a subsurface structure, the systemincluding a base unit, mobile satellite nodes and sensor stations linkedby a fiber optic cable.

FIG. 2 shows a schematic view of a portion 2 of the system of FIG. 1depicting the mobile satellite node and sensor stations in greaterdetail.

FIG. 3 shows a schematic view of a seismic acquisition unit.

FIG. 4 is a flow chart depicting a method of monitoring seismicparameters of a subsurface structure.

DETAILED DESCRIPTION

The description that follows includes exemplary apparatuses, methods,techniques, and instruction sequences that embody techniques of thesubject matter. However, it is understood that the described embodimentsmay be practiced without these specific details.

Systems and methods for integrated seismic monitoring are provided. Theintegrated system includes a base unit, a plurality of mobile satellitenodes, and a plurality of sensor stations. A fiber optic cable joins thebase unit to the multiple mobile satellite nodes distributed about asurface location for interactive operation therebetween. Each of themobile satellite nodes has sensor stations for collecting seismic datarelating to a subsurface formation. A single light source at the baseunit may be used to send and receive a laser light to each seismicsatellite node. The information from each of the seismic satellite nodesmay be collected and manipulated at the base station.

FIG. 1 schematically depicts a system 100 for monitoring seismicparameters of a subsurface structure 102. The system 100 includes a basestation (or camp) 104, multiple mobile satellite nodes 106 and multiplesensor stations 108. The base station 104 may be a consolidated orcentralized location for controlling operations throughout the system100. Operators may be stationed at the base station 104 for performingmanual and/or automatic operations throughout the system 100. The mobilesatellite nodes 106 may optionally be unmanned with operators located atthe base station 104 for controlling operations at each of the satellitenodes 106.

The satellite nodes 106 may be seismic trucks or other mobile devices orvehicles deployable to various surface locations about the subsurfacestructure 102. Each satellite node 106 may have array (or seismic array)cables 120 linked to multiple sensor stations 108 for collecting seismicdata. A seismic cable 110 extends from the base station 104 and to eachof the satellite nodes 106. The seismic cable 110 may be deployed fromthe base station 104 on a reel and extended to each of the sensorstations 108 for communication therewith. A communication network may beformed by linking the base station 104 to the satellite nodes 106 andthe sensor stations 108 via the seismic cable 110. The seismic cable 110may be a unitary cable, or multiple cables joined together to form asingle cable. Connectors for joining cables are described in U.S. Pat.No. 6,827,597.

Any cable capable of communicating between the base station 104 and thesensor stations 108 may be used. The seismic cable 110 may be, forexample, a conventional fiber optic cable used in seismic surveying.Conventional fiber optic cables, such as a steel armored optical cablewith optical fibers inside gel-filled stainless steel tubes, may beused. In some cases, portions of the integrated seismic system may haveadditional or other communication links using wired or wirelesscommunication links therebetween.

The base station 104 may have a light source 112 including a laser foremitting a laser light 111 through the seismic cable 110. Examples oftechniques for passing laser light through a fiber optic cable aredescribed in U.S. Pat. No. 7,622,706. A seismic detector 114 may beprovided for detecting changes in the laser light 111. A processor 116may also be provided for analyzing the changes and determining seismicparameters therefrom. A seismic acquisition unit 118 may be provided atthe base station 104 for receiving the light 111 and determining seismicparameters therefrom as will be described further herein. The satellitenodes 106 may be provided with the same capabilities of the base station104 for operating independently thereof as desired.

A selected length of optical cable 110 may be used to carry light fromthe light source, which is distributed to the various sensor stations108 in the seismic system 100. The light in the sensor stations 108experiences a change or phase shift related to the physical propertybeing measured. Changes in optical characteristics of the optical fiberscauses changes in the properties of the applied light which may bedetected by one of a number of different optical measurement techniques.Optical signals from the sensor stations 108 are then collected andreturned to a receiving device for demultiplexing and analyzing thesignals from each sensor station 108.

Examples of fiber optic cables are provided in U.S. Pat. No. 6,850,461.The fiber optic cable may use wavelength-division multiplexing (WDM)and/or frequency division multiplexing (FDM) techniques in which opticalsplitting of source light from an input bus to individual sensors andrecombination of signals from the individual sensors are made indiscrete modules, such that optical splicing and splitting orrecombining components are mechanically isolated from other portions ofthe cable. Portions of the cable and/or sensor stations may bereplaceable to address any failures that may occur in the system.

A seismic source 119 may be provided for producing impact, vibration,explosion or other seismic events to generate seismic waves through thesubsurface structure 102. Conventional seismic sources, such as aseismic vibration truck may be used (see, e.g., US Patent ApplicationNo. 2009/0238038). In some cases, the seismic satellite nodes 106 may becapable of generating seismic waves in the subsurface structure 102. Theintegrated seismic system 100 may be positioned about the seismic source119 and/or subsurface structure 102 for measuring seismic parametersgenerated by the seismic source 119.

A data network ring may be set up from the base station 104 to thesatellite nodes 106 to communicate the status of the system 100 duringthe seismic acquisition. The integrated seismic system 100 may form aseismic network about the surface of the subterranean structure. One ormore satellite nodes 106 may be linked to the base station 104 to formthe network. The satellite nodes 106 may be positioned at variouslocations about the surface of the subsurface structure 102. The seismiccable 110 may extend from the base station 104 to the satellite nodes106 in series or in discrete intervals.

As shown in FIG. 1, the satellite nodes 106 form a continuous loopextending from the base station 104 to each of the satellite nodes inseries and back to the base station 104. The satellite nodes 106 may bepositioned in various configurations, such as the loop (or ring), astar, a linear, and/or other configurations. Various combinations ofcontinuous and/or linear configurations may be used to provide a varietyof configurations. The light source 112 at the base station 104 may emita light 111 for passing through each of the satellite nodes 106 andreturning to the base station 104. In a continuous configuration, suchas a loop, ring or star, the light 111 may pass through the fiber opticcable 110 and continue to the seismic acquisition unit 118 therein asindicated by the dashed arrow. In a linear configuration, the lightsource 112 may emit a light 111 therethrough and receive it backtherethrough. As indicated by the two way solid arrow, data may passboth ways through system 100 via the seismic cable 110.

The satellite nodes 106 may be processing units with, for example, abouta 72,000 channel capacity. Acquisition survey needs may require systemshaving about one million or more channels. Multiple satellite nodes 106may be deployed for providing the necessary channel capabilities. Theintegrated network formed by the system 100 may be used to operate thechannels provided by multiple satellite nodes 106 from a singlelocation. The seismic acquisition unit 118 may be used to receive andprocess the data from the multiple nodes and to perform necessaryquality control (QC) and operational control. The integratedconfiguration provided by the system 100 may be used to compare datafrom multiple sources, eliminate redundancies, and provide an integratedanalysis of the data.

FIG. 2 shows a schematic view of a portion 2 of the seismic system 100of FIG. 1. This figure also shows one of the satellite nodes 106(depicted as a seismic truck) and the sensor stations 108 in greaterdetail. As shown, multiple array cables 120 extend from the satellitenode 106, with each array cable 120 having multiple sensor stations 108.The sensor stations 108 may be operatively connectable to the satellitenode 106 for interaction therewith. The sensor stations 108 may becarried by the seismic cable 110, or connected thereto at the surfacelocations. The sensor stations 108 may be conventional optical sensorspositionable about the surface locations for measuring seismicparameters of the subsurface structure 102. The optical sensors may be,for example, hydrophones, accelerometers, or geophones, for sensingphysical properties, such as subsurface motion, energy or changes inpressure. The sensor stations 108 may have radio frequencyidentification (RFID) tags R containing information, such asidentifiers, for each sensor station.

The sensor stations 108 may be connected to a sensor pad on the seismiccable 110. By way of example, the sensor pads may be located about every25 m along the seismic cable 110. The sensor stations 108 may bepositioned at various locations and used to generate an optical signalin response to the sensed physical properties. The optical signal maybe, for example, a change in wavelength, a change in phase or aninterference pattern in response to changes in the physical parameter.Examples of optical sensor stations are provided in U.S. Pat. Nos.7,154,082, and 6,549,488. Multiple sensor stations 108 may bemultiplexed from the light source 112 at the base station 104 and signalreturn optical fibers using optical telemetry systems.

As shown in FIG. 2, the seismic cable 110 enters the satellite node 106from the base station 104 and is split out into the array cables 120.The seismic cable 110 continues through the satellite node and on to thenext satellite node(s) and back to the base station 104. Communicationwith the base station 104 may be provided with the satellite node 106and/or sensor stations 108 for determining seismic parameters. The laserlight 111 may pass through the seismic cable 110, through the satellitenode 106 and out on to the base station 104 as indicated by the dashedarrows. The laser light 111 is also directed through the sensor cablesand returned back to the satellite node 106. When the laser light 111passes from the base station 104 to the satellite nodes 106, thesatellite nodes 106 collect, amplify and redistribute the light.

The seismic cable 110 may also be used to pass data between thesatellite node 106 and back to the base station 104 as indicated bybidirectional arrows. The data may be directed to the seismicacquisition unit 118 of FIG. 1. The satellite node 106 may house its ownseismic acquisition unit 218 for collecting and recording seismic datafor its sensor stations 108. The seismic acquisition units 118 and/or218 may receive the light 111 that passes to the sensor stations 108 andis returned therefrom, and may determine seismic parameters as will bedescribed further herein. The seismic acquisition unit 218 may have partor all of the functionality of the seismic acquisition unit 118 of FIG.1.

FIG. 3 is a schematic view of system architecture that may be used asthe seismic acquisition unit 118 of the base station 104 of FIG. 1and/or the seismic acquisition unit 218 of the satellite node 106 ofFIG. 2. The seismic acquisition unit 118/218 includes electroniccomponents including an acquisition management system 330, aQC/Processing System 332, recording media 334, 335, spread &optoelectronics 336, a source controller 338, and an acquisitionrecorder (or generic acquisition system (sometimes referred to as“gAS?”)) 340. Various links may be provided between the electroniccomponents for operative connection therebetween.

The source controller 338 provides communication between an operator atthe base station and the satellite nodes 106. Data from the satellitenodes 106 is passed from the source controller 338 to the acquisitionmanagement system 330. The acquisition management system 330 providescommunication between an operator at the base station 104 and thesatellite nodes 106. Data from the satellite nodes 106 is passed back tothe acquisition management system 330. The acquisition management systemmay also communicate with the source controller 338 to provide vibratorinformation to be stored along with the data. The acquisition managementsystem 330 acts as a central processing unit (CPU) for processing all ofthe data of the seismic acquisition unit 118/218. The acquisitionmanagement system 330 also communicates with the QC/Processing system332 and the spread & optoelectronics 336. The QC/Processing system 332may be a network computer used for data manipulation, such as signalprocessing, visualization of data, etc. Data from the QC/Processingsystem 332 may be passed to an individual record storage 334 forrecording. The individual record storage 334 may be a recording media,such as tape drives for storing the data.

The spread & optoelectronics 336 receives signals from the satellitenodes 106 and converts the signals into seismic data for recording. Theseismic data may be passed from the spread & optoelectronics 336 to theacquisition recorder 340 for formatting by an Ethernet connection. Theacquisition recorder 340 formats the seismic data for recording. Theformatted data may be passed to a recording media 335, such as acontinuous data storage, for recording. The data storage 335 may be arecording media, such as a raid drive for storing the data.

The system architecture enables the seismic acquisition and QC functionsto take place in the centralized base station 104. The satellite nodes106 may also perform certain functions, such as initial quality control(QC) functions, at the seismic acquisition unit 218 and report statusback the seismic acquisition unit 118 of the base station 104 where themain control takes place. Information may be provided at multiple levelsto provide redundancy, cross-checks, and interpretation.

The seismic acquisition unit 118/218 may also be used to collectinformation from the RFID tags R of the sensor stations 108. Thecomputers in the system and/or additional RFID units may be provided tocommunicate with and/or collect information from the RFID tags. The RFIDtags R may be scanned by an RFID unit (not shown) during or afterdeployment to the field 102 to identify the RFID unit by location alongthe surface location 102. The RFID unit may also have an RFID sensor forreceiving data from and logging the sensor stations. This informationmay be used with the data collected by the seismic cable 110 and/orsensor stations 108 to, for example, correlate seismic data withlocation and/or sensor information specific to the identified sensorstation 108.

The seismic acquisition unit 118/218 may have processors/computers toprovide such correlations. For example, the seismic acquisition unit118/218 may have a global positioning satellite (GPS) tracker thatgathers information from the RFID tags that may be used to plot aposition of the sensors using. Information concerning a location of eachsensor may be determined using conventional GPS technology linked to anoutput from each sensor station 108. The GPS data may provide positiondata in a three dimensional axis. Z-axis data may provide elevationinformation so that the sensor stations may be corrected to a similarflat datum. X-axis and Y-axis data may position data so that digitalfilters can be provided to remove additional error. The gathered GPSdata for each sensor station may be correlated with the data collectedby the sensor station for further analysis. The analyzed information maybe used to determine subsurface properties at a given location.

In operation, dense wavelength division multiplexing (DWDM) may be usedin the integrated seismic system 100 to optically power the sensorstations 108. By way of example, an optoelectronic cabinet may beassembled using 10 wavelengths with the capacity to run 960 sensor or240 4C channels. Multiplexed and modulated light 111 may be sent intothe seismic cable 110 and the array cables 120 to the sensor stations108. The light 111 returning from the sensor stations 108 may bedemultiplexed and demodulated. A phase modulated laser light 111 passesthrough an interferometer in the sensor station 108. Stress from theoutside world causes a phase shift in the light 111 as it passes throughthe interferometer. Using the seismic acquisition system 118/218, thephase information is extracted from the returning light to output asignal equivalent to the stress input at the sensor station 108. Thisprovides a passive system with no electronics.

The light source 112 generates the optical power for the array of sensorstations 108, and processes the returned optical signals to extract theseismic information. Light 111 returning from the sensor array cables120 may be routed to a select group of demodulation boards to processthe optical data, and outputs a ‘word’ (e.g., a 32-bit digital word)equal to the seismic data. The data may be processed by the seismicacquisition unit 118 (e.g., a network interface card), where it is putinto data packets, and sent to the data storage 334, 335.

FIG. 4 is a flowchart depicting a method 400 of monitoring seismicparameters of a subsurface structure 102. The method 400 involvesproviding an integrated seismic system such as the system 100 of FIG. 1(e.g., including a base station 104 and a plurality of satellite nodes106 and a plurality of sensor stations 108). The method also involvespositioning (482) the satellite nodes and the sensor station about asurface location, generating (483) a seismic disturbance at the surfacelocation, linking (484) the mobile satellite nodes and the sensorstation with a seismic cable, passing (486) a light from the laserthrough the optical cable, collecting (488) seismic data from thesubsurface structure with the sensor station by detecting disturbancesin the light, and receiving (490) seismic signals at the base stationfrom the mobile satellite nodes via the seismic cable and generatingseismic parameters therefrom.

The method may also involve analyzing the measured seismic parameters.Other steps may also be performed, such as performing a quality controlcheck, and/or capturing and/or correlating information from the sensedRFID tags with the subsurface data collected by the sensor stations. Thesteps may be performed automatically or manually, in any order andrepeated as desired.

While the present disclosure describes configurations, numerousmodifications and variations will become apparent to those skilled inthe art after studying the disclosure, including use of equivalentfunctional and/or structural substitutes for elements described herein.For example, aspects of the subject matter may include two or moreseismic trucks (or nodes) connected by one or more seismic cables, andhave one or more sensor stations.

Plural instances may be provided for components, operations orstructures described herein as a single instance. In general, structuresand functionality presented as separate components in the exemplaryconfigurations may be implemented as a combined structure or component.Similarly, structures and functionality presented as a single componentmay be implemented as separate components.

1. An integrated seismic system for monitoring seismic parameters of asubsurface structure, the integrated seismic system comprising: aplurality of mobile satellite nodes, each of the plurality of mobilesatellite nodes having sensor stations operatively connectable theretofor collecting seismic data from the subsurface structure; a seismiccable operatively linking the plurality of mobile satellite nodes andthe sensor stations; and a base station comprising a seismic acquisitionunit for receiving seismic signals from the plurality of mobilesatellite nodes via the seismic cable and generating seismic parameterstherefrom.
 2. The integrated seismic system of claim 1, wherein theseismic cable comprises a fiber optic cable and wherein the base stationcomprises a light source for sending and receiving a light through thefiber optic cable.
 3. The integrated seismic system of claim 2, whereinthe fiber optic cable comprises a plurality of fiber optic sectionscoupled together into a continuous fiber optic cable.
 4. The integratedseismic system of claim 1, wherein the seismic cable links the basestation to the plurality of mobile satellite nodes in series.
 5. Theintegrated seismic system of claim 1, wherein the plurality of mobilesatellite nodes comprise a plurality of seismic trucks.
 6. Theintegrated seismic system of claim 1, wherein the seismic acquisitionunit comprises recording media for collecting the measured seismicparameters.
 7. The integrated seismic system of claim 1, wherein theseismic acquisition unit comprises a source controller.
 8. Theintegrated seismic system of claim 1, wherein the seismic acquisitionunit comprises an acquisition management system.
 9. The integratedseismic system of claim 1, wherein the seismic acquisition unitcomprises spread and optoelectronics.
 10. The integrated seismic systemof claim 1, wherein the seismic acquisition unit comprises anacquisition recorder.
 11. The integrated seismic system of claim 1,where the seismic cable links the plurality of mobile satellite nodes tothe base station in one of a looped configuration, a linearconfiguration, a star configuration, a concentric ring configuration andcombinations thereof.
 12. The integrated seismic system of claim 1,where each of the sensor stations are connected to the plurality ofmobile satellite nodes by an array cable.
 13. The integrated seismicsystem of claim 1, wherein each of the sensor stations comprises a radiofrequency identification tag.
 14. An integrated method for monitoringseismic parameters of a subsurface structure, comprising: providing anintegrated seismic system comprising a base station and a plurality ofmobile satellite nodes, each of the plurality of mobile satellite nodeshaving sensor stations operatively connectable thereto; linking theplurality of mobile satellite nodes and the sensor stations with aseismic cable; collecting seismic data from the subsurface structurewith the sensor stations; and receiving seismic signals at a basestation from the plurality of mobile satellite nodes via the seismiccable and generating seismic parameters therefrom.
 15. The method ofclaim 14, further comprising sending and receiving a light from a lightsource at the base station through the seismic cable and to the sensorstations
 16. The method of claim 14, further comprising analyzing themeasured seismic parameters.
 17. The method of claim 14, furthercomprising processing the measured seismic parameters.
 18. The method ofclaim 14, further comprising generating a seismic disturbance at thesurface structure.
 19. The method of claim 14, further comprisingcorrelating a position of the sensor stations with the seismic data.